Ethernet switches provide a redundant network infrastructure

21st February 2013

Ethernet switches from GarrettCom Europe are playing a key role in securing future energy supplies, by providing a redundant network infrastructure for a new floating LNG storage and regasification terminal off the coast of Italy. The plant will provide up to 5 per cent of Italy’s annual requirement.

The current high prices for crude oil and petroleum based products are helping to focus attention even more sharply on alternative fuel products, with LNG (liquefied natural gas) rising to the fore as a viable alternative to help meet the world’s energy needs.

Cooling natural gas to –162°C at normal pressure results in the condensation of the gas into liquid form. LNG takes up about one six hundredth of the volume of gaseous natural gas, making transportation and storage economical, so making it cost-effective to tap remote natural gas deposits.

Global demand for gas has tripled in the past 30 years as nations look for more secure energy supplies, and the International Energy Agency has predicted a further doubling in the next 30 years. By 2030, gas will be supplying a quarter of our energy needs.

A new project to construct an LNG storage and regasification terminal offshore, off the coast of Livorno, Italy will soon begin operation, providing a total annual capacity of 3.75 billion cubic metres. The terminal is built around an LNG tanker converted to provide both storage and regasification, anchored 12 miles off the coast of Livorno. It will receive and store LNG from other LNG carriers, and convert it back into gaseous form. The gas will then be transported onshore via a subsea pipline to enter the Italian national distribution network.

In 2004, OLT (Offshore LNG Toscana) spa – the development company set up for the project – commissioned Golar LNG to convert the Golar Frost LNG tanker into the required floating storage and regasification terminal.

The LNG terminal conversion ship is a steel mono hull with Moss LNG tanks arranged in the middle, the regasification plant in the forward section and crew facilities with control room and utility machinery in the aft section. The terminal is equipped with four spherical, 13cm thick aluminium LNG tanks, designed to ensure optimum stability of the terminal and make it virtually immune to any effects of the waves. The regasification plant is the heart of the project, and is essentially a heat exchanger. Sea water passing through the heat exchangers heat up the LNG by the few degrees needed to return it to gaseous form. The chilled water is returned to the sea: studies have shown that the cooler water will extend only a few metres from the ship, and will run out completely 40-50 metres from the ship.

The gas is transported to the mainland through 36km of pipeline, of which 29.5km is subsea at a maximum depth of 120m.

A vital aspect of the project was the control system, which manages the transfer of LNG from transportation vessels to the terminal, the regasification process and the delivery of gas to the mainland, and many of the terminal’s other critical operational functions. The control system had to be built around a dual-redundant network certified to Italy’s ESS-SotoStazioniElettriche standards (implementations of IEC-61850 and IEEE-1613) and offering the highest levels of reliability. To meet these requirements, Italian systems integrator Fort Fibre Optic recommended a fibre optic LAN built around Ethernet switches from GarrettCom Europe.

For the LNG terminal, GarrettCom Europe supplied 6K32TRC (managed) and ES42H-2SC (unmanaged switches), all configured for 24V DC power. The 6K32TRC is a 32-port, free-convection-cooled rack-mount Ethernet switch. Specially designed for applications where rack space is at a premium or where strict EMI/EMC regulations preclude the use of conventional fan cooling, the 6K32TRC uses innovative casework design and patented thermal management techniques to ensure the highest levels of operating safety in hazardous environments.

The 6K32TRC managed switch provides 16 fixed 10/100Mb copper ports plus two modular slots which can be freely configured to best meet user requirements. The modular slots can accommodate a mixture of 10/100Mb copper ports, 100Mb fibre ports and Gigabit ports. For example, users can specify up to a further 16 10/100Mb copper ports to give 32 in all, or between one and four Gigabit ports, mixing and matching as required. Gigabit ports can be configured for a variety of fibre and copper cabling types and distances.

The ES42H is a compact, hardened and rugged edge switch that provides a total of six Ethernet ports. Four are always RJ-45 copper ports, and the remaining two can be user specified as two 100Mb fibre ports, or one fibre and one copper port, or two copper ports. The ability to connect these edge switches in either ‘star’ or ‘ring’ configuration using non-proprietary self-healing protocols such as RSTP-2004 was one of the key strengths of the GarrettCom products in this application.

The terminal is expected to be fully operational in 2011. Its authorised capacity is 3.75 bcm, but this can be extended to 5.25 bcm. Italy has scarce natural resources of its own, and relies on natural gas imports to cover about 85% of its needs. The Livorno terminal will contribute to a more secure energy supply in the country, removing the risk of shortage of supply through traditional pipelines.